Tension device



C. T. EVANS.

TENSION DEVICE.

APPLICATION FILED MAY 28, 1914.

1,343,91 O. Patented June 22, 1920.

aawpul'ork W M E; 5mm

' had to the accompanying drawing, forming 7 maintain the web or other material supplied UNITED STATES" PATENT OFFICE.

' CLARENCE T. EVANS, OF MILWAUKEE, WISCONSIN, ASSIGNOB TO THE CUTLER- I HAMMER MFG. 60., OF MILWAUKEE, WISCONSIN, A CORPORATION OI WIS- cousin.

'rENsIoN :onvrcn.

To all whom it may concern Be it known that I, CLARENCE T. Events, a citizen of the United States, residing at Milwaukee, in the county of Milwaukee and State of Wisconsin, have invented new and useful Improvements in Tension Devices, of which the following is a. full, clear, concise, and exact description, reference being a art of this specification his invention relates to lmprovements 1n tensioning devices and is particularly ap-- plicable to printing presses, although it may obviously be advantageously employed in other relations.

The invention has among its objects to provide means automatically tending to to the receiving machine under given tension at all times,

A further object is to provide means of the aforesaid character which will act upon relatively slight variations in tensionand which will also act with varying rapidity according to the degree of tension variation.

Various other objects and advantages of the invention will hereinafter appear.

The invention may, in practice, be embodied in various different forms, one of which has been schematically illustrated in the accompanying drawing.

Referring to the drawing, the same shows a roll 1 of web or other suitable material to be fed to a press or other receiving machine, exemplified by cylinders 2. As the material is withdrawn from the roll 1 it is passed over a yielding fixed roll 3, then beneath an adjustable roll 4: and over a second fixed roll 5 to the press or other machine 2.

The adjustable roll 4 constitutes a tension device automatically adjustable to different positions according to the amount of slack between the rolls '3 and 5. It is carried by a frame 6 pivotally supported by a bracket 7 and connected by a spring 8 to an adjustable'device 9. The spring 8 biases the tension roll 4 downwardly against the web,

Application filed m 28,

varies the tension of the web and the follow-i ing means are provided to rectify such varia- Specification of Letters Patent. Patented J tin 0 22, 1920. I

1914. serial No. 841,618.

tions and thereby tend to maintain the given f tension. The core or shaft of the roll l'is connected as by a belt 10 to the armature A of a shunt wound (1 machine is adapted to act either as a generator to electrically brake the roll or as a motor to drive said roll and is governed by a rheostat R. The rheostat R is in turn automatically controlled by themovement of the tension device 4; to govern the machine M in accordance with the movement of said device for the purposes hereinafter set forth.

The rheostat has a pivoted arm 18 operatively connected, as by means of a belt 14:, to a shaft 15, in turn operatively connected to a driving shaft 16 through a worm 17 and worm wheel 18. The shaft 16 is mounted in bearings 19 and has splined thereto a friction vwheel 20 cooperating with a friction disk 22 rotatable with the webroll 1, although if preferred said disk may be driven from some other source, as, for example, the press or independent means. The arrangement is such that the friction wheel 20 is movable longitudinally of the shaft 16 and-diametrically across the disk 22 to establish a reversible drive from the disk 22 to the shaft 16 and to vary the speed ratio between said members. For efi'ecting such movement of the friction wheel the same is provided with an operating lever 23' fulcrumed to a bracket 24: and connected by a link 25 to a bell crank extension 26 of the tension frame 6. The arrangement is such that in normal position of the frame 6 the friction wheel 20 is disposed centrally of .the friction disk to be inert, When, however, the tension device moves in either direction from its normalposition it moves the friction wheel in a corresponding direction radially of the friction disk and to a degree proportional to the degree of movement of said tension device. Accordingly, the rheostat R is thereby operated in one direction or the other accordin to the movement of said tension device and at a speed varying with and proportional to the degree of movement of said tension device. More specifically as the tension device falls it affects movement 7 reverse operation of the rheostat tends to of the rheostat armin a clockwise direction and as it rises effects movement of the rheostat arm in a counter-clockwise direction.

The rheostat arm carries contacts to elec-- trically connect a contact segment 27 with series to parallel relation with respect to the armature. As is well understood, this tends to cause the machine to act as a motor, while slow down the machine and when it is overhauled by its load to cause it to act as a dynamic brake.

The mechanism as a whole operates as fol lows: Assuming that the web is being drawn into the press under the desired tension with the rheostat arm in the position illustrated, the machine M will act as a generator, being driven by the roll and therefore act as a dynamic brake for the roll. Under such conditions, should the press slow down, causing an increase in slack with a consequent drop ping of the tension roll, the friction wheel would be moved tothe right, thereby effecting clockwise movement of the rheostat arm. This would result in an increase of the series resistance and a decrease of the shunt resistance, which would further increase the braking efiect of the machine M to slow down the web roll. If the increase in slack was large the tension device would cause a relatively large movement of the friction wheel with a consequent accelerated speed of the rheostat. On the other hand, if the increase in slack was slight, then the movement imparted to the friction wheel would be pro portionally slight and the speed of the rheostat proportionally low. Thus the action of the rheostat is suited to the need and as the roll is slowed down and the excessive slack taken up the friction wheel is returned toward neutral position to gradually slow down and stop the rheostat arm. However, the rheostat arm is stopped only when the tension device is restored to normal position, with a consequent restoration of normal tension. After restoration of normal tension the rheostat arm remains inert until the tension device again falls or rises.

Assume now that the slack in the web decreases either through an increase in the speed of the press or a decrease in the size of the roll. Under such conditions the tension device would be raised with a resulting operation of the rheostat in a counter-clockwise direction. This, as above set forth, would decrease the braking effect of the machine M, permitting the-web roll to accelerate. Also, as above set forth, this move ment of the rheostat in thisdirection tends to cause the machine M to act as a motor. Hence, should the elimination of the braking effect fail to effect restoration of normal conditions, then said machine would act' as a motor to drive the roll. This action, however, would be unlikely to occur unless the roll had been reduced to a relatively small diameter. Again, it will be observed that the rheostat is operated at a speed proportional to the degree of movement of the tension device, and is gradually slowed down and stopped as the tension device returns to normal position.

Hence, throughout the feeding of the web the mechanism would pass through one or the other of the aforesaid cycles of operation upon each variation in tension, thereby tending at all times to maintain the tension at the desired predetermined value.

Assume now that the press is stopped, or that the web breaks. Under such conditions there is a tendency for the roll, especially if large, to continue to rotate. This would result in an increased slack with a consequent dropping of the tension device and operation of the rheostat in a clockwise direction. This, in turn, would gradually increase the efi'ectiveness of the machine M as a brake and, if the momentum of the roll was suflicient, would return the rheostat to dotted line position, giving the maximum braking effect. Quick stopping of the roll would thereby be insured.

ln restarting the roll 1 the machine M, of" course, acts according to the position of the rheostat and hence according to the position of the tension roll 4;. However, it always permits the roll to be readily started, for, even in braking position of the rheostat said machine has no braking efiect upon the roll until after the latter is set inmotion.

What I claim as new and-desire to secure by Letters Patent is: V

1. In a tension mechanism for printing press rolls and the like, in combination, a mechanism having a positive power connection with the roll and operative through 1'15 said connection for driving and braking the roll selectively and a governor operable in accordance with variations in tension of the material delivered by the controlled roll for varying the action of said mechanism.

2. In a tension mechanism for printing press rolls and the like, in combination, means for selectively driving and braking the roll and governing means therefor responsive to variations in the slack of the material drawn from the roll, said latter means selecting the action of said former means and varying the action .thereof according to both the character and degree of slack variation.

3. In a tension mechanism for printing press rolls and the like, in combination, -a

dynamo-electric machine having a positive powerv connection with the rol and automatic governing means therefor responsive to variations in tension of the material sup-'1,

plied from the roll to cause said machine to act alternatively as a driver or as a brake for the roll.

4. In a tension mechanism for printinggress rolls and the like, in combination, a ynamo electric machine having an operative connection, with the roll aird automatic controlling means therefor responsive to variationsin the slack of the material drawn from the roll to cause said machine to act alternatively asa driver or as a brake according to the character of the slack variations.

5. Inv a tension mechanismfor printing ress rolls and the like, in combination, a dynamo-electric machine-having an operative connection with the roll and automatic controlling meanstherefor responsive to variations in the slack of the material drawn from the roll to cause said machine 'to act alternatively as a driver oras a brake according. to the character of theslack variation and to a degree corresponding with the degree of slack variation.

6. In a tension mechanism for printing. press rolls and the like, in combination, means for alternatively driving or brakingthe roll and means responsive to variations in the slack'of the material drawn from the roll to vary the action of said former means and to maintain the variation thus effected.

during restoration of normal slack and until sub uent variation thereof.

7 n a tension mechanism for printing press rolls and the like, in combination, means for alternatively driving or dynamically braking the roll and governing means therefor responsive to variations in the tension to act thereon in reverse ways but selectively according to the character of tension variation from a given value.

8.- In a tension mechanism for printing press rolls and the like, in combination,

means for alternatively driving or braking the roll, a slack device, and governing means for said driving or braking means operable in reverse directions in response to move-= ment of said slack device but uni-directional within certain ranges of said device irrespective of the direction of movement of the latter.

9. In a tension mechanism for printing press rolls and the like, in combination, a

dynamo-electric machine having an oper-,

ative connection with the roll and automatic means responsive to tension variations to cause said machine to act alternatively as a driver or as a brake, said eans upon -effecting an adjustment of said machine in 3 selectively fires me to a ten sion variation maintaining suc adjustment during restoration of nortion in tension. v

10.T he combi 'ation with; tensioning dynamo-electric machine operatively connected to the roll of material to 'dynami cally brake the same and upon variations in the slack in the we mal tension and until.;asubsequent variameans for mater I drawn from a roll, of a governing means .for said machine automatically 1 o' 'r'able combination th anemi means for material drawn from a roll,- of a dynamo-electric machine operatively connected to the roll of material to electrically brake the same and said machine automatically operable up'on variations in tension and in. either oftwo ways according to thecharacterlof the ten- -sion variation. v

12. In combination, tensio '"means formaterial drawn from a roll, a ynamo-electric machine operatively connected to the verning means for roll to drive or dynamically brake thefsame and controlling means for said machine operable automatically upon variations in tension and'in different ways and at different speeds according-to the character and de cc of tension variation.

13. n combination, tension' for material drawn from a 1611,! ynamo-elec tric machine operatively connectedto the" roll of material anda'power and dynamic braking controller for said machine governed in operation by movementof a part of said tension device. v

14. In combination, tensionin means for material drawn from a roll, a ynamo-elecq tric machine operatively connectedto the roll of material, a power and dynamic ment of a pm of said tension device.

, 15. In-combination, tensionin means for material drawn .froma roll, inc uding a device automatically djustable upon variations in slack, a dynamo-electric machine operatively connected with the roll of material, a power and dynamic braking controller for said machine and operating means for said controller governed by said adjustable debraking controller for said machine and opv.eratmg means for said controller verned in speed and direction ofoperation y-move- 17. In combination, tensionin means for material drawn from a roll, inc uding a device automatically adjustable upon variations in tension and to a degree proportional to the tension variation, a dynamo-electric machine operatively connected to the roll of material, a power and dynamic braking controller for said machine and operating means for said controller ineffective in a given 0- sition of said device and rendered effective upon movement of said device from said given osition.

18. n combination, tensioning means for material drawn from a roll including a device automatically adjustable upon variations in tension and to a degree proportional to the tension variation, a d namo-electric machine operatively connecte to the roll of material, a power and dynamic braking controller for said-machine and means whereby said controller is operated in different directions and at varying speeds upon movement of said device in opposite directions from a given position and 1s rendered inert when said device assumes said given position. I L i In witness whereof I have hereunto subscribed my name in the presence of two witnesses.

CLARENCE T. EVANS. 

